1. Field of the Invention
The invention relates generally to a float/guide member which is adapted to be mounted between a mother printed circuit board and a card edge connector. More particularly, the invention pertains to a float/guide member which is uniquely adapted to receive the contact pins of the edge connector, allowing the pins to extend through the float/guide member and into the mother printed circuit board, whereby the card edge connector is able to move or float laterally on its contact pins with respect to the mother printed circuit board. The latter characteristic allows a daughter board associated with the card edge connector to be properly aligned and mated with a second card edge connector mounted remotely either on the mother printed circuit board or on a separate printed circuit board.
A typical problem attendant with mother printed circuit boards provided with an in-line series of fixed card edge connectors is that they exceed the pad width tolerances on daughter boards and, when a daughter board is plugged into the connectors, open and shorted daughter board connections are apt to occur. When tighter tolerance pitch connectors, such as a 2.times.120 0.050 inch pitch card edge connector, is placed in-line with a smaller card edge connector, such as a 2.times.6 0.100 inch pitch connector, the problem of daughter board connections is even more prevalent, as is the case where one daughter board plugs into two card edge connectors on different printed circuit boards.
The subject invention addresses and overcomes the foregoing problems by providing means enabling a card edge connector to float laterally, so that a single daughter board can plug into in-line card edge connectors of different pitch, as well as into card edge connectors of different printed circuit boards. The invention accomplishes this objective by providing a float/guide member which is adapted to be disposed between a 2.times.6 0.100 inch pitch connector and a mother printed circuit board. The float/guide member includes a plurality of contact receiving cavities, into which the card edge connector pin contacts are intended to be press fit inserted.
Each of the contact pins extends through a narrow opening at the bottom of its contact receiving cavity in the float/guide and into a mother printed circuit board, being soldered thereto. The contact receiving cavities in the float/guide member are enlarged above the narrow bottom opening, whereby the contacts are able to bend or float within their contact receiving cavities. The invention contemplates lengthening the card edge connector pin contacts, and thinning the contact beam perpendicular to the direction of the float. Thinning and extending the card edge connector contacts allows the lateral float movement without additional mechanical or solder connections.
The float/guide member thus allows the card edge connector with which it is associated to move or float laterally on its thinned contact pins, generally around .+-.0.05 inch. Raised parallel side rails provided on the upper portion of the float/guide member prevent movement of the card edge connector perpendicular to the transverse plane so as to minimize stress on the thinned pin contacts. Moreover, maximum lateral movement of the card edge connector is defined by the size of the oversized contact receiving cavities, thereby limiting contact fatigue.
When the card edge of a daughter printed circuit board is vertically inserted into the card edge connector, lateral floating of the card edge connector made possible by the float/guide enables the daughter printed circuit board to be properly aligned with and plugged into a second, different pitch card edge connector mounted on the mother printed circuit board in-line with the first edge connector. Additionally, the capability of the first card edge connector for lateral float permits the daughter printed board to be plugged into a second card edge connector mounted on a second, different printed circuit board.
2. Description of the Prior Art
It is known in the prior art to provide edge connectors for printed circuit boards. Examples of such connectors are disclosed in U.S. Pat. No. 3,008,113, U.S. Pat. No. 3,193,791 and U.S. Pat. No. 3,264,598.
U.S. Pat. No. 3,264,598, which issued on Aug. 2, 1966 to Phelps et al. discloses a connector which extends longitudinally along the adjoining longitudinal edges of a pair of circuit boards and is provided with a slot for receiving an edge of each of the circuit boards.
U.S. Pat. No. 3,008,113, which issued to Johnson on Nov. 7, 1961, shows a receptacle which receives a pluggable printed circuit board and which is electrically connected to a second printed circuit board.
U.S. Pat. No. 3,193,791 to Bock et al., bearing an issue date of Jul. 6, 1965, teaches a receptacle provided with a card receiving cavity for receiving the terminal end of a printed circuit board.
The prior art further discloses a card edge connector characterized by a wedge which serves to bias a card edge inserted into the connector against the far end wall of the card receiving slot. As shown in U.S. Pat. No. 4,766,805 of Oct. 11, 1988 to Brown et al., a nose provided on the wedge biases the card edge, and a spring associated with the wedge urges the wedge away from the backplane on which the connector is mounted.
It is also known in the prior art to provide an adapter for a card edge connector to accommodate a warped card edge. U.S. Pat. No. 4,204,737, for example, which issued on May 27, 1980 to Faber et al., discloses a molded plastic adapter having a first slot for receiving a terminal support block, and a second slot defined by opposing guide portions for receiving and straightening a warped leading edge of a substrate.
Finally, the prior art teaches a connector system for interconnecting two modules characterized by a pin guide which reduces the tolerance mismatch of the pins associated with two different modules. In particular, Moore, U.S. Pat. No. 3,850,492 dated Nov. 26, 1974, shows a pin guide having funnel-shaped entrance passageways to allow reception of male pins despite a mismatch between the modules. Moore is further characterized in that receptacles in the female connector are adapted to float within the connector.
The prior art fails to teach or suggest a float/guide member inserted between a card edge connector and a printed circuit board and being adapted to receive the pin contacts of the card edge connector whereby the card edge connector is able to float laterally on its contacts with respect to the printed circuit board and the float/guide member.